[10A2] Automated scanning ultrasound testing of brazing
G Por1, M Agócs1, E Kocsó1, J Molnar1, P Szabó1, K Szikszai1 and M Szabó2
1University of Dunaujvaros, Hungary
2Oerlikon Eldim (HU) Ltd, Hungary
Some construction metal sheets are fixed together using brazing. Keeping the plates near to each other and heating them, the brazing material due to capillarity flow between the plates makes a relatively strong coupling when it fills the total gap. However, when we have only partly good penetration down to 50-40% then the adhesion is not strong enough to keep together the plates, and one plate can be detached from the other during the lifetime of the instrument. One needs a non-destructive method to check the percentage of void in brazing. We developed a scanning acoustic microscope (SAM) mechanically moving the immersion ultrasound head with precision and step of 100 microns. Measuring the A-scan in each position all together we can map the brazing with precision better than 100 microns. Making 2D pictures at levels of brazing we can precisely map the area when the brazing is good and bad with resolution of 0.1 mm. Finally, we automatically estimate the area of good and bad adhesion of the brazing material, consequently to estimate the strength of brazing. We present some detail of SAM and several pictures of bad and good examples. Validation of the method was carried out by peeling off one plate from the other and a visual check proves the precise mapping made by the NDT method.
